A power battery is a power source that provides power to tools, often referring to the batteries that power electric vehicles, electric trains, electric bicycles, and golf carts. It differs primarily from the starting battery used to start car engines, and typically employs valve-sealed lead-acid batteries, open-type tubular lead-acid batteries, and lithium iron phosphate batteries.
Currently, the main types of power batteries used in new energy vehicles are: lithium-ion batteries, nickel-metal hydride batteries, fuel cells, lead-acid batteries, and sodium-sulfur batteries.
Lithium-ion batteries
A lithium-ion battery is a rechargeable battery that primarily functions by the movement of lithium ions between the positive and negative electrodes. During charging and discharging, Li+ ions repeatedly insert and extract between the two electrodes: during charging, Li+ ions extract from the positive electrode, pass through the electrolyte, and insert into the negative electrode, leaving the negative electrode in a lithium-rich state; the reverse occurs during discharging.
Based on the different electrolyte materials used in lithium-ion batteries, lithium-ion batteries are divided into liquid lithium-ion batteries (LIB) and polymer lithium-ion batteries (PLB).
Lithium-ion batteries have high energy density and high average output voltage. They have low self-discharge; good batteries show less than 2% self-discharge per month (which is recoverable). They have no memory effect. They have a wide operating temperature range of -20℃ to 60℃. They exhibit excellent cycle performance, can be charged and discharged quickly with a charging efficiency of up to 100%, and have high output power. They have a long lifespan. They do not contain toxic or harmful substances and are known as green batteries.
Nickel-metal hydride batteries
Nickel-metal hydride (NiMH) batteries are high-performance rechargeable batteries. They are classified into high-voltage and low-voltage types. The positive electrode active material is Ni(OH)₂ (called the NiO electrode), the negative electrode active material is a metal hydride, also known as a hydrogen storage alloy (the electrode is called the hydrogen storage electrode), and the electrolyte is a 6 mol/L potassium hydroxide solution.
The positive electrode active material of a nickel-metal hydride battery is Ni(OH)₂ (called the NiO electrode), and the negative electrode active material is a metal hydride, also known as a hydrogen storage alloy (the electrode is called the hydrogen storage electrode). The electrolyte is a 6 mol/L potassium hydroxide solution. The main manufacturing processes for the active materials forming the electrode sheets include sintering, slurry drawing, nickel foaming, nickel fiber fabrication, and intercalation. Electrodes prepared using different processes exhibit significant differences in capacity and high-current discharge performance. Batteries are generally manufactured according to the specific application conditions and manufacturing processes.
fuel cells
A fuel cell is a chemical device that directly converts the chemical energy of fuel into electrical energy; it is also known as an electrochemical generator. It is the fourth type of power generation technology after hydropower, thermal power generation, and nuclear power generation. Because fuel cells convert the Gibbs free energy portion of the fuel's chemical energy into electrical energy through an electrochemical reaction, they are not limited by the Carnot cycle effect, resulting in high efficiency. Furthermore, fuel cells use fuel and oxygen as raw materials; and since they have no mechanical transmission parts, they produce no noise pollution and emit very few harmful gases. Therefore, from the perspective of energy conservation and environmental protection, fuel cells are the most promising power generation technology.
lead-acid batteries
Lead-acid batteries (VRLA) are rechargeable batteries whose electrodes are primarily made of lead and its oxides, and whose electrolyte is sulfuric acid solution. In the discharged state, the positive electrode is mainly composed of lead dioxide, and the negative electrode is mainly composed of lead; in the charged state, both the positive and negative electrodes are mainly composed of lead sulfate.
A single lead-acid battery cell has a nominal voltage of 2.0V, can discharge to 1.5V, and can be charged to 2.4V. In applications, six single lead-acid batteries are often connected in series to form a lead-acid battery with a nominal voltage of 12V. There are also 24V, 36V, and 48V batteries.
Sodium-sulfur batteries
Sodium-sulfur batteries are secondary batteries that use Na-beta-alumina (AL2O3) as the electrolyte and separator, and metallic sodium and sodium polysulfide as the negative and positive electrodes, respectively. Sodium-sulfur batteries have unique advantages for energy storage, mainly reflected in low raw material and manufacturing costs, high energy and power density, high efficiency, no site restrictions, and convenient maintenance.
Sodium-sulfur (NaS) batteries, as a novel chemical power source, have seen significant development since their inception. They are small in size, have large capacity, long lifespan, and high efficiency, and are widely used in power storage applications such as peak shaving, emergency power, and wind power generation.
